Some semiconductor devices have a multiplicity of large current power elements such as power transistors arranged in close proximity (see for example Japanese Patent Early Publication No. H7-135299).
These multiple large current power elements are often required to have their relative variations in characteristics reduced. One way to reduce the relative variations is shown in FIG. 8.
FIG. 8 shows an arrangement of a semiconductor integrated circuit 200 having two power transistors 1A and 1B. Operating conditions of the power transistors 1A and 1B are controlled by respective control signals supplied, via signal lines 3A and 3B, from respective control circuits 2A and 2B each having a signal-processing circuit and a pre-drive circuit. The output end of the power transistor 1A is connected to an output pad 5A via an output wire 4A, and the output end of the power transistor 1B to output pad 5B via an output wire 4B. The power input ends of the power transistors 1A and 1B are connected to a common power supply pad 7 via power supply wires 6. The power input end may be alternatively connected to the ground. In this case, the power input ends serve as grounding ends, the power supply wires 6 as grounding wires, and the power supply pad 7 as a grounding pad. This applies to the rest of the examples shown below.
In the conventional semiconductor device 200, the power transistors 1A and 1B are arranged as close as possible to each other. However, no matter how closely the power transistors 1A and 1B are arranged to each other, corresponding portions of the power transistors 1A and 1B (indicated by Xa and Xb in FIG. 8 for example) will be separated by an appreciable distance, since the power transistors 1A and 1B themselves have large areas. In addition, the semiconductor substrate in which the power transistors 1A and 1B are built has impurity gradient induced during its manufacture. Variations in characteristics of the power transistors 1A and 1B due to the impurity gradient and distance are unavoidable. Similarly, variations in the characteristics due to a temperature gradient created in the semiconductor substrate during operation are unavoidable.